The water pressure transfer method is one in which a transfer film having a predetermined water-insoluble print pattern applied onto a water-soluble film is floated on a water surface within a transfer tub while the water-soluble film is made wet with the water and an article (a transferred body or a body to be pattern-transferred) is immersed into the water within the transfer tub while it contacts the transfer film whereby the print pattern of the transfer film is transferred onto the surface of the article using the water pressure to thereby form a decorative layer. Generally, since the ink of the print pattern is in a dry state because of the transfer film having the print pattern previously printed and formed on the water-soluble film, it is required to apply an activation agent or a thinner to the print pattern of the transfer film on the transfer operation so as to activate the ink of the print pattern in order to get the same wet state of the ink (the state where it has an adhesion) as the state of the ink immediately after being printed. This is generally referred to as activation. In addition thereto, in order to provide wear resistance, solvent resistance, medicine resistance and weather resistance, etc. to the decorative layer formed on the surface of the article, it is necessary to form a transparent surface protection layer (topcoat layer) on the decorative layer.
With the surface protection layer formed on the decorative layer, since, the whole surface of the article has gloss provided thereon so as to have a design depth given thereto and therefore, there is imparted a kind of high-class feeling such as a polished one on the product which is the water pressure transfer article with the result that there is provided an effect of design expression. However, the whole appearance surface has the uniform glossy feeling and for example, there cannot be expressed a true wood feeling or a qualitative feeling similar to the quiet taste and the elegant simplicity in a grain pattern to cause the limit of design expression. On the other hand, even if the decorative layer is exposed without any surface protection layer formed thereon, there cannot be necessarily expressed the true wood feeling or the qualitative feeling similar to the quiet taste and the elegant simplicity and even though this can be expressed, the product has the poor wear resistance, solvent resistance, medicine resistance and weather resistance, which cannot become the final product. Thus, in practice, the surface protection layer has been applied to the product at the sacrifice of the design expression.
With the surface protection layer formed on the decorative layer, in some cases, there is produced a slippery feeling when a person contacts the surface thereof or a low grade feeling and therefore no surface protection layer might be applied to the decorative layer in one technique. However, in the same manner as the aforementioned design expression, in order to obtain the wear resistance, solvent resistance, medicine resistance and weather resistance, the surface protection layer has been applied to the product at the sacrifice of the design expression.
Such being the case, the applicant considers that it will probably be very difficult to solve the problems such as the aforementioned design expression and the surface feeling and had tried to solve various subjects in the water pressure transfer techniques problems while these problems such as the design expression and the surface feeling are shelved.
In one prior art, the surface protection layer is formed by applying by spray urethane 2 liquid type coating material, acrylics lacquer type coating material or ultraviolet ray hardening type coating material onto the decorative layer and then irradiating an ultraviolet ray on the ultraviolet ray hardening type coating material to thereby harden the coating material.
In this process, however, the decorative layer itself has the solvent resistance not improved, but the surface protection layer (the topcoat layer) to overcoat the decorative layer has the wear resistance, solvent resistance, etc., born for the decorative layer. Since the urethane 2 liquid type coating material is applied after transferring the print pattern and then water-washing and drying the print pattern, it will take relatively longer time to perform these processes and in addition thereto, since the drying is done while exposed to a hot wind, dust will be possibly adhered onto the decorative layer, which disadvantageously lowers the appearance of the decorative layer.
In a second prior art, there has been proposed a method in which water pressure transfer of the print pattern and formation of the surface protection layer are carried out at the same time (see the first patent document). This method is the one in which a transfer film with a protection layer is formed by applying a transparent or semi-transparent surface protection layer of water-insoluble resin on a water-soluble film and then a water-insoluble print layer on the surface protection layer and the transfer film with the protection layer is transferred under water pressure onto an article (a body to be pattern-transferred).
According to this method, since the surface protection layer and the print layer on the water-soluble film are simultaneously transferred on the surface of the article when it contacts the transfer film using water pressure on the water pressure transfer operation, this method can omit the steps of applying and hardening the protection coating material after the transfer process, which have been required in the first-mentioned conventional art, and can avoid dust from adhering between the decorative layer and the surface protection layer.
In this manner, this method can be advantageously used because the surface protection layer is formed at the same time when the print layer is transferred whereby the steps of operation can be simplified and in addition thereto the appearance of the decorative layer is never deteriorated and also the surface protection layer can provide the wear resistance to the surface of the print layer of the article to thereby physically protect it because the surface protection layer is formed of a protection agent of low solvent resistance such as butyl-methacrylate or ethyl-methacrylate, but the surface protection layer disadvantageously has the poor chemical protection because it is easily deteriorated when it contacts various solvents or medicines.
There has been proposed another prior art that is similar to the second prior art, but is different from the latter in that the material for the surface protection layer of the second prior art is replaced by a resin to be hardened by an ultraviolet ray, etc (see the patent document 2).
In the third prior art, since the resin hardened by the ultraviolet ray etc. is used for the surface protection layer, it will physically and chemically protect the decorative layer in an effective manner, but it has some undesirable disadvantages when the adhesion of the print pattern, which is the uppermost surface of the transfer film is recovered or reproduced as described later.
More particularly, although it is common on the aforementioned first to third prior arts, an activation agent or a thinner is applied to the print pattern of the transfer film to recover the adhesion of the print pattern when the transfer should be carried out, but since the activation agent or the thinner has an organic solvent contained therein, the time in which the solvent ingredient completely volatilizes and the drying condition are required to be considered as the process conditions and an adverse influence may be provided to the quality of the water pressure transfer article if the solvent ingredient remains in the print layer after the transfer of the print pattern. Furthermore, since the organic solvent is emitted into the atmosphere during the operation or inhaled by the human body, using the organic solvent for activating the print pattern causes organic air pollution or health injury of laborers and this becomes such a problem as should be solved immediately.
As the inventors tried to directly apply such an ultraviolet ray hardening type coating material as used in the first prior art, which is also an eco-friendly coating material, they could discover the recovery of temporary adhesion of the ink in the print pattern of the transfer film, but also find that when it tries in a continuation work during the water pressure transfer process, it becomes poor transfer due to the reduced adhesion of the print pattern. It has been discovered that as the same trial is performed using an ultraviolet ray hardening type ink which contains the same ultraviolet ray hardening resin composite as the ultraviolet ray hardening type coating material does, but contains no coloring agents, the adhesion of the ink in the print pattern can be recovered and that the transfer can be performed without reduction of the adhesion even during the transfer process.
In case of the water pressure transfer, not only the ink in the print pattern has the wet state returned so as to recover the adhesion of the ink, but also the water-soluble film having the print pattern supported thereon is made also wet with the water in the transfer tub whereby both of the print pattern and the water-soluble film are required to be easily attached onto and around the surface of the article when it is forced into the water. Thus, the article should be forced underwater at the time when the wet states of both of the print pattern and the water-soluble film are obtained. The adhesion of the print pattern to attach the print pattern onto the article should be maintained until the transfer is completed.
The inventors surmise that the difference between these trial results is caused by the difference between the composition of the ultraviolet ray hardening type coating material and that of the ultraviolet ray hardening type ink as the products different from their usage even though they contain the same ultraviolet ray hardening resin composite. In addition thereto, they surmise that there is the difference in that the ultraviolet ray hardening type coating material contains low boiling point solvent, but the ultraviolet ray hardening type ink generally contains less solvent, and therefore, as the ultraviolet ray hardening type coating material is applied to the print pattern, the original adhesion of the print pattern can be recovered by the solvent in the coating material, but the adhesion will be reduced due to the evaporation of the solvent when the transfer is carried out and since the ultraviolet ray hardening type ink has no solvent, any non-solvent composite will serve to recover the print pattern. The applicant has proposed the method to solve various problems of the prior arts by repeating various experiments under the aforementioned suppositions.
This method of solving the problems comprises a step of applying a non-solvent type ultraviolet ray hardening resin composite on the print pattern of the transfer film to recover the adhesion of the print pattern by a non-solvent activation component of the non-solvent ultraviolet ray hardening type resin composite, a step of forcing the article underwater together with the transfer film so as to force the print pattern containing the ultraviolet ray hardening type resin composite onto the surface of the article and a step of irradiating an ultraviolet ray on the article on which the print pattern containing the ultraviolet ray hardening type resin composite is transferred whereby the ultraviolet ray hardening type resin composite is hardened in the state where the ultraviolet ray hardening type resin is wholly united with the print pattern to form a decorative layer.
The applicant confirms while the invention is completed that the decorative layer itself of the water pressure transfer article obtained by this water pressure transfer method has at least the adhesion to the surface of the article and the solvent resistance and therefore can be commercially produced even without any surface protection layer.
Also, the applicant confirms that the water pressure transfer article obtained by this water pressure transfer method has the expression of design variation of the decorative layer accomplished.
Initially explaining the expression of design variation of the decorative layer, when there is observed the decorative layer formed by transferring the print pattern of grain, for example under water pressure, a glossy feeling can be observed in a layer portion where an early wood portion is expressed, but no glossy feeling is seemingly observed in a layer portion where a late wood portion is expressed by printing black ink of high density. The applicant finds that the existence of the different glossy feelings adjacent to each other can impart a cubic affect of real wood to the surface of the article.
It will be guessed that the variation in the glossy feeling will occur due to the following causes. That is, since the ultraviolet ray hardening resin composite coated on the surface of the transfer film for recovering the adhesion of the print pattern on the water pressure transfer is absorbed by the coloring pigments or the like in the black ink, the ultraviolet ray hardening resin composite is hardened by the ultraviolet ray so as to expose a particle feeling (fine unevenness) of the pigments in the position (layer portion) where the black ink is transferred at high density whereby the glossy feeling is reduced, but in the position where the ink other than the black ink is transferred and the black ink is transferred at lower density, the ultraviolet ray hardening resin composite is hardened by the ultraviolet ray while it is seldom oil-absorbed by the pigments so as to be buried between the components of the pigments whereby fine unevenness is reduced so as to maintain the glossy feeling. The applicant supposes that the variation in the glossy feeling will be generated by the aforementioned causes. Thus, thereafter, various confirmation experiments are repeated in view of the supposition.    [Patent Literature 1] JP04-197699A    [Patent Literature 2] JP2003-305998A
A first fundamental object of the invention is to provide a water pressure transfer article adapted to impart adhesion and mechanical and chemical surface protection functions such as solvent resistance, etc., to a decorative layer itself on the article without any surface protection layer (topcoat layer) formed thereon and also adapted to improve a glossy variation on the surface of the decorative layer.
Another object of the invention is to provide a water pressure transfer article adapted to impart a three dimensional or cubic effect to a decorative layer based on a difference of glossy feelings by having a portion where there is the glossy feeling on the decorative layer and a portion where there is reduced the glossy feeling on the decorative layer.
Further object of the invention is to provide a water pressure transfer article adapted to impart a three dimensional or cubic effect to a decorative layer based on a difference of glossy feelings so as to have real wood sense, qualitative sense, reality sense, novel sense, strange sense and effects such as the quiet taste and the elegant simplicity whereby there can be imparted many design expressions, which the prior art has not had.
Further object of the invention is to provide a water pressure transfer article adapted to impart mechanical and chemical surface protection functions to a decorative layer itself on the article and to improve a glossy variation on the surface of the decorative layer.